Hydrobranchiata
Hy`dro*bran`chi*a"ta\, n. pl. [NL., fr. Gr. "y`dwr water + ? gills.] (Zo["o]l.) An extensive artificial division of gastropod mollusks, including those that breathe by gills, as contrasted with the Pulmonifera. -- Hy`dro*bran"chi*ate, a.